Investigating the acute effects of black carbon, PM2.5 exposure, and temperature on asthma and respiratory-related emergency department visits and hospitalizations in Mississippi

Globally, exposure to air pollutants (black carbon (BC) and fine particulate matter (PM_2.5)) is associated with respiratory diseases, however, research is limited in the Southern United States, particularly in Mississippi. This study investigated the influence of BC, PM_2.5, and temperature on daily asthma and respiratory emergency department visits and hospital admissions among individuals ≥65 years old in the Jackson, Mississippi Metropolitan Statistical Area (MSA), over a two-year period. Time-series analysis explored the exposure-lag-response relationship between environmental factors and asthma and respiratory outcomes. During the study period, a total of 1466 asthma-related and 9482 respiratory disorder-related admissions were recorded with females representing 74 % of asthma-related and 59 % of respiratory disorder-related admissions. An interquartile range (IQR: 1.42 μg m^-3) increase in BC concentration was associated with an increased risk of respiratory disorder-related admissions at lag 0, with a RR of 1.013 (95 % CI: 1.001-1.026) for all data, and an RR of 1.020 (95 % CI: 1.003-1.038) for the female subgroup. Neither BC nor PM_2.5 was identified to be associated with asthma-related admissions. Springtime exposure to an IQR increase in BC (1.42 μg m^-3) and PM_2.5 (6.91 μg m^-3) significantly increased the risk of asthma-related admissions at lag 1, with a RR of 1.490 (95 % CI: 1.207-1.840) and 1.471 (95 % CI: 1.010-2.143), respectively. Lower temperatures increased the risk of respiratory disorder-related admissions, with elevated RRs observed 10-25 days post-exposure. This study indicates that BC exposure, particularly among females, was more strongly associated with respiratory disorder-related admissions than PM_2.5 exposure. Temperature variations exhibited a significant impact on respiratory disorder-related admissions compared to asthma-related admissions. BC revealed a significant antagonistic interaction with temperature, while PM_2.5 showed no interaction. Identifying environmental factors affecting human health in disparity-prone areas like Mississippi is crucial to protect public health.